Question

Question 1
Which of the following is an endothermic process?
a) freezing of water
b) fuel burning in a car engine
c) combustion of cooking gas
d) vaporization of water

Question 2
Which of the following signs on q and w represent a system that is doing work on the surrounds, as well as losing heat to the surroundings?
a) -q, -w
b) +q, +w
c) +q, -w
d) None of the above
e) -q, +w

Question 3
Lead, water, sulfur and arsenic have specific heats of 0.128, 4.18, 0.706 and 0.329 J/goC, respectively. Which of these would require the smallest amount of heat to increase its temperature by 10 oC (assume all samples have the same mass)?
a) Lead
b) Sulfur
c) Arsenic
d) All them will require same amount of energy
e) Water

Question 4
Use the \DeltaΔHof values provided in the textbook to calculate \DeltaΔHorxn for the following:
SO2Cl2(g) + 2 H2O(l) --> 2 HCl(g) + H2SO4(l)                \DeltaΔHorxn = ?
SO2Cl2(g) (\DeltaΔHo = -354.8 kJ/mol)
a) -72.2 kJ
b) 256 kJ
c) -1556 kJ
d)512 kJ

Answer 1

Question 1 :

Endothermic process :

The process in which heat is absorbed is called as endothermic process.

Vaporization of water needs energy in order to break intermolecular interaction and vaporization is endothermic process.

Q.2

We use sign convention to answer this question.

When system does work on the surrounding then the sign of the w should be negative When work is done on the system then the sign of work is positive. When heat is given out from system then sign of q is negative and when heat is taken by system the sign would be positive.

Q. 3

Specific heat is the amount of heat required to raise the temperature of substance weighing 1 g by 1 degree C. So the substance that has less value of specific heat will required smallest amount of heat to increase its temperature by 10 degree C.

The answer would be lead.